Hunko said: "Kennedy wanted to infiltrate anti-fascists, and [act] as an agent provocateur to instigate actions together with them. I suspect, then, that it wasn't Scotland Yard that focused his interest on the 'hot spots' of the German anti-fascist scene. I see proof instead of the opposite: that the German police were involved in the operation of this British agent."

Earlier this week, Hunko called on the Bundestag to reveal what the authorities knew about Kennedy's infiltration of German protest groups.

Today, he said: "The government has denied the opportunity to disclose information relating to my official question of the government. In view of the continually increasing evidence of illegal activities, I demand that the operations of Kennedy within Germany be illuminated."

Similar calls have been made in Ireland, where Kennedy spent some time between 2004 and 2006.

Hunko said he knew of at least one case in which Kennedy offered his "help" in Germany. He said: "To an activist living in Germany, Kennedy had offered that when there was a 'Nazi problem', that he could come with 'his friends' to take care of it. Kennedy then expected that the activist should give him hints."

Hunko also accused Kennedy of starting sexual relationships with activists and helping to organise the German end of the G8 and G20 protests.

The Guardian revealed on Monday how Kennedy had lived deep undercover at the heart of the environmental protest movement for seven years, travelling to 22 countries, gleaning information and playing a frontline role in high-profile confrontations.

Hunko's researcher, Matthias Monroy, said he had met Kennedy three times in Berlin over the past nine years. He said Kennedy had been active in Dissent!, an international network of local groups that came together to organise opposition to the G8 summit at Gleneagles, Perthshire, in July 2005.

Monroy said Kennedy appeared to have been scouting for information right up to his unmasking: "Last year, one or two months before his true identity was discovered, I know that he sent emails to organisers of other protests asking what the plans were for the G20 summit in France in 2011."

The claims echo findings from other activists, who say Kennedy travelled through Europe under his adopted identity as a "freelance climber". This week it emerged that he had been a regular visitor to Ireland, Iceland and Spain.